TROPICAL MAPPING

The aim of the project was to develop specific products from ERS SAR and InSAR data, in view of increasing their utilization for operational applications in tropical countries. The main goal of the project was to estimate the areal extent of irrigated rice fields, which is an important parameter for yield forecasting.

Rice is cultivated in about 110 countries on five continents. There are 50 countries that have an annual production of at least 100,000 tons of rice per year. Asia accounts for 90% of the world’s production and consumption of rice because of its favourable hot and humid climate.

Conventional methods for rice monitoring are based on ground collected statistics, which have proved time consuming, inaccurate and expensive. Spaceborne remote sensing offers an effective alternative to these traditional methods through operational, weather independent systems utilizing Synthetic Aperture Radar technology. These techniques allow an efficient mapping and monitoring of rice crops over large areas at regular and frequent intervals.

Due to frequent cloud cover in tropical areas, optical imagery cannot be used for an operational mapping and monitoring service. However, active microwave instruments like SAR instruments on-board ERS-1/2 and ENVISAT platform operate independently of weather conditions and solar illumination.

An approach using SAR and interferometric SAR data acquired by ERS-1/2 has been tested in the area of Polonnaruwa (Sri Lanka). In parallel, investigations about market needs for rice maps generated from satellite imagery was carried out.

The major result of the project was SARscape® , a tailor-made software for land applications, which can be used for rice mapping and rice growth monitoring. The modular SAR processing chain was embedded in the commonly used ArcView® (Environmental Systems Research Institute, Inc.) Geographic Information System environment and allowed novice users, even if not at all familiar with SAR technology, to generate thematic products such as rice maps and to monitor the rice growth in an automatic way.